Hi, I'm after help in trying to solve a problem, my ABS light has decided to stay on, at first the light was coming on intermittently, but now it's on all the time.
Any ideas ?

Jack

gunnerMontreal

Joined: 04 Jul 2014Posts: 617Location: Kent

Posted: Sat Sep 02, 2017 8:44 pm Post subject:

From memory it's usually either a sensor or alternator issue.

My came on when the alternator belt gave up the ghost.

I'm sure someone will be along soon with a more convincing answer though._________________993 C2 Tip Aventura

9xxnickSilverstone

Joined: 29 Jul 2014Posts: 134

Posted: Sat Sep 02, 2017 10:46 pm Post subject:

There could be other causes, but my recent experience was that a faulty wheel speed sensor (one per wheel) causes the ABS control unit to switch the light on immediately before and after starting the engine.

If the light only comes on when the car gets to around 4mph, then the wheel speed sensors are electrically OK but are dirty, resulting in there being no or a corrupted signal to the ABS CU.

The sensor are not especially expensive but are generally a pig to remove from the wheel hub, sadly.

ToreBApproved Trader

Joined: 13 May 2010Posts: 552Location: Oslo, Norway

Posted: Sun Sep 03, 2017 7:12 am Post subject:

Use a Porsche compatible OBD diagnosis device to read out the fault code in the unit. This will probably point you directly to the problem.
Cheers,
Tore_________________'95 993 C4

Thanks for the replies.
I've just connected a ohmmeter to each wheel sensor, the rear o/s gives no reading at all, so I'm presuming this is the most likely culprit?
The other issue I've just noticed is that the odometer has also stopped working, the speedo works fine, could these two issues be linked ?
Jack D

PretzelHockenheim

Joined: 20 Apr 2014Posts: 644Location: Bedfordshire

Posted: Sun Sep 03, 2017 5:35 pm Post subject:

Jack D wrote:

Thanks for the replies. The other issue I've just noticed is that the odometer has also stopped working, the speedo works fine, could these two issues be linked ?
Jack D

Probably not related, odometers tend to stop working around the 100k mark usually because of a worn Gear wheel, speedo usually follows.

There is a do it yourself fix, but most people send the speedo to Julian Reap.

Thanks for the replies.
I've just connected a ohmmeter to each wheel sensor, the rear o/s gives no reading at all, so I'm presuming this is the most likely culprit?
The other issue I've just noticed is that the odometer has also stopped working, the speedo works fine, could these two issues be linked ?
Jack D

Hi,

I had my speedo odometer repaired last year. I found the guy on Ebay UK, he did a good job, was knowledgeable and did a quick turn a round. The contact is :

The total cost including shipment to Spain was £90.00 I think the repair was £75.00.

ATB _________________1995 993 C2 Cab TipS in Guards Red

Jack DMonza

Joined: 05 Jul 2011Posts: 175

Posted: Tue Sep 05, 2017 9:18 am Post subject:

The rear abs sensors you now have to buy in pairs from porsche main dealers.
The old type have been discontinued, the new type apparently are wired differently and need to be replaced in pairs....a pair from porsche will set you back just under £400.
Sourcing the old type is proving difficult, especially in the uk, I've found a parts dealer in the states who still has a few genuine ones on the shelf.

Jack D

Jack DMonza

Joined: 05 Jul 2011Posts: 175

Posted: Tue Sep 05, 2017 9:21 am Post subject:

decgraham wrote:

Jack D wrote:

Thanks for the replies.
I've just connected a ohmmeter to each wheel sensor, the rear o/s gives no reading at all, so I'm presuming this is the most likely culprit?
The other issue I've just noticed is that the odometer has also stopped working, the speedo works fine, could these two issues be linked ?
Jack D

Hi,

I had my speedo odometer repaired last year. I found the guy on Ebay UK, he did a good job, was knowledgeable and did a quick turn a round. The contact is :

The total cost including shipment to Spain was £90.00 I think the repair was £75.00.

ATB

GaitySilverstone

Joined: 25 Sep 2008Posts: 118Location: Mid-Wales and Sunderland

Posted: Tue Sep 05, 2017 8:37 pm Post subject:

Jack D wrote:

The rear abs sensors you now have to buy in pairs from porsche main dealers.
The old type have been discontinued, the new type apparently are wired differently and need to be replaced in pairs....a pair from porsche will set you back just under £400.
Sourcing the old type is proving difficult, especially in the uk, I've found a parts dealer in the states who still has a few genuine ones on the shelf.

Jack D

You have to replace in pairs (if you have old version) because the sensor bars in the new version are 90 degrees different, so I guess there would be a slight signal mismatch if you only replaced one on an axle. I replaced my rears and sourced from Promax Motorsports - less than £50 each.

Jack DMonza

Joined: 05 Jul 2011Posts: 175

Posted: Wed Sep 06, 2017 10:52 am Post subject:

I have tried them, unfortunately they're closing down the business....
just going to start drilling out the other sensor, no doubt that one is seized in as well.

Jack D

GaitySilverstone

Joined: 25 Sep 2008Posts: 118Location: Mid-Wales and Sunderland

Posted: Wed Sep 06, 2017 12:11 pm Post subject:

Jack D wrote:

I have tried them, unfortunately they're closing down the business....
just going to start drilling out the other sensor, no doubt that one is seized in as well.

Jack D

That's a shame - they have been handy for several parts over the years

Yes, it will be seized!

Jack DMonza

Joined: 05 Jul 2011Posts: 175

Posted: Tue Sep 12, 2017 7:46 pm Post subject:

Just an update...
New rear sensors fitted and no warning light !
If your ABS light comes on, use a multi meter and check each sensor, simple test to eliminate or pinpoint a defective sensor.

Jack D

berni29Watkins Glen

Joined: 24 Oct 2009Posts: 2175Location: Kent

Posted: Mon Sep 25, 2017 3:03 pm Post subject:

Hi

Well done drilling then out. I have done this more than once and its a job I hate. I also burn them out a bit to help them along the way. At least the new ones ate plastic rather than metal bodied and do not seize in place.

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